Synthesis gas, or syngas, may be produced by reacting solid or liquid or gaseous carbonaceous fuels with gases such as air, enriched air, or oxygen, in the optional presence of steam or water in a gasification reactor. The syngas obtained is withdrawn from the gasification reactor and subjected to several cleansing operations to rid it of various contaminants which are formed or liberated from the carbonaceous fuels during the gasification operation. For example, materials often found in the syngas include hydrogen sulfide, ammonia, cyanides, various halogens and particulates in the form of carbon, ash, and coal, as well as trace metals.
Particulate solids, i.e. carbon, soot, and ash, entrained in the hot raw gas stream from a partial oxidation gas generator can be removed by quench cooling the hot gas stream directly in water in a quench drum and by scrubbing with water in a gas scrubbing zone. By this means, a syngas stream and a dispersion of particulate solids i.e. carbon and ash are produced. It is economic to reclaim the water in the aforesaid dispersion by removing particulate solids and gaseous impurities and recycling the reclaimed water for use in the gas quench cooling and scrubbing operations. However, the levels of impurities and particulates in such reclaimed water are still too high to enable its general use in gasification subsystems that would otherwise require a supply of fresh water, such as in pump flushing systems and various instrumentation systems including level and flow detection systems.
Therefore, although the prior art has utilized various methods and devices for reclaiming water from a gasification system, such systems have not been able to remove a sufficient quantity of the gaseous impurities and particulates so as to allow the general use of the reclaimed water in place of fresh water in those gasification subsystems that would otherwise require a source of fresh water.